Abstract

Saccharomyces cerevisiae had ability to accumulate heavy metal from solutions. Saccharomyces cerevisiae which used as heavy metal adsorbent was fermentation waste biomass from alcohol plant due to economic considerations. These adsorbent would be degradated in solutions. This weakness could be overcome by immobilizing the adsorbent with silica gel. The objectives of this research was to determine optimal weight ratio of adsorbent to silica gel in immobilization process. Weight ratio of adsorbent to silica gel used are 5 : 1, 5 : 2, 5 : 3, 5 : 4, and 1 : 1. Batch adsorption was done by contacting cadmium solution and adsorbent which had been immobilized in shaker bath for 2 hours. Sample was analyzed with Atomic Absorption Spectrometer (AAS). Rate of degradation was done by contacting aquadest and immobilized adsorbent in a three necks glass and an extractor equipped. The research result that optimal weight ratio of adsorbent to silica gel are 5 : 2 for the maximum cadmium adsorption and 5 : 3 for the slowest rate of degradation. Keywords : adsorption, cadmium, immobilized, alcohol plant waste biomass, Saccharomyces cerevisiae